Soldering apparatus of a reflow type

Abstract

A soldering apparatus of the reflow type contains a preheating chamber and a reflow chamber which are provided with a plurality of heaters for heating printed circuit boards with chips temporarily mounted thereon with solder pastes during conveyance by a conveyor. The heaters are provided with a screening member and/or a partition member so as to prevent direct radiation of radiant heat from the heaters into the chambers and onto the printed circuit boards and to provide a uniform air flow to be blown uniformly onto the printed circuit boards. The heaters are arranged so as to heat them in such a manner as to increase temperatures in the direction from an inlet to an outlet so as to become higher with a predetermined temperature differential from the previous heater, thus removing bubbles generated upon fusion of the solder pastes and minimizing heat shock to the chips as they are heated. The preheating chamber is further provided with a combustion unit with a catalyst for removing fume and odorous gases generated in the chamber and for circulating the heated air after removal of such fume and gases. These arrangements can provide printed circuit boards of higher quality and with high productivity.

What is claimed is: 
     
       1. In a solder apparatus of the reflow type having a conveyor means for conveying a printed circuit board on which a chip is temporarily mounted with a solder paste, a preheating chamber for preheating the printed circuit board, a reflow chamber for effecting soldering of the chip on the printed circuit board by fusion of the solder paste, and a fan for circulating air in each of the chambers, the improvement comprising, for each of the preheating chamber and the reflow chamber: a heater mounted on a sidewall of the chamber   a screening member mounted adjacent to said heater to prevent direct radiation of heat into the chamber, and to form with said sidewall a heating sub-chamber;   an air inlet for directing air into said sub-chamber to be heated by said heater, and an air outlet for directing heated air to the circulating fan;   an air discharge disposed adjacent to said conveyor means for discharging heated air from said chamber onto said conveyor means and printed circuit board; and   as air flow transforming member disposed in said air discharge for transforming turbulent air flow to laminar air flow to provide a uniform flow of heated air from said discharge.   
     
     
       2. A soldering apparatus as claimed in claim 1, further comprising a combustion unit with a catalyst for removing smoke and odoring gases generated in the preheating chamber and circulating heated air to the preheating chamber. 
     
     
       3. In a soldering apparatus of the reflow type having a conveyor means for conveying a printed circuit board from an outlet to an outlet on which a chip is temporarily mounted with a solder paste, a preheating chamber for preheating the printed circuit board, a reflow chamber for soldering the chip on the printed circuit board by fusion of the solder paste and a fan for circulating air in each of the chambers, the soldering apparatus comprises: a plurality of heaters mounted at an air outlet portion of the preheating chamber and spaced apart in parallel to the direction of conveyance of the conveyor means for heating air to be blown onto the printed circuit board being conveyed by the conveyor means, at increasingly higher temperatures from the inlet to the outlet of the conveyor means, so as to heat the printed circuit board with a predetermined temperature differential:   a plurality of heaters mounted at an air outlet portion of the reflow chamber and spaced apart in parallel to the direction of conveyance of the conveyor means for heating air to be blown onto the printed circuit board being conveyed by the conveyor means, at increasingly higher temperatures from the inlet to the outlet of the conveyor means, so as to heat the printed circuit board with a predetermined temperature differential; and   a partition member mounted so as to separate each of the plurality of the heaters in the preheating chambers and in the reflow chambers so as to provide a flow of air heated therein to be blown onto the printed circuit board being conveyed by the conveyor means and to retain a predetermined temperature differential between adjacent separate spaces in which each of the heaters is disposed.   
     
     
       4. A soldering apparatus as claimed in claim 3, further comprising: a screening member mounted adjacent to each of the heaters in the preheating chamber and in the reflow chamber so as to prevent direct radiation of the radiant heat into each of the chambers and to the printed circuit board.   
     
     
       5. A soldering apparatus as claimed in claim 4, further comprising a combustion unit with a catalyst for removing smoke and odorous gases generated in the preheating chamber and for circulating heated air to the preheating chamber. 
     
     
       6. A soldering apparatus as claimed in claim 3, further comprising a combustion unit with a catalyst for removing smoke and odorous gases generated in the preheating chamber and for circulating heated air to the preheating chamber.